It looks to me that your issue is with folders with names that work in Outlook but that break rules elsewhere. So X1, as I said earlier, and as you now confirm, treats your "/" character as a space.
As your quest is not so much to find messages but to find these folders and then give them names that don't upset other stuff, I return to my earlier suggestion about using Outlook to find these folders. If you search for messages in them, then you will be able to locate their "roots". That done you can change the names.
One thought is that Windows Search might find these folders. If that does not work, then that just confirms my view that you need to take drastic action and to rename the folders.
Looking at Outlook's own search, I see that it has an option to search "In Folder". I don't have folders with that character in them. (I renamed my own folders with wonky characters because I found that they broke stuff.) But you could try that as a way of dining the folders. If Outlook is prepared to break the rules of Windows in naming files, maybe it will also break the rules when you want to find them.
As your quest is not so much to find messages but to find these folders and then give them names that don't upset other stuff, I return to my earlier suggestion about using Outlook to find these folders. If you search for messages in them, then you will be able to locate their "roots". That done you can change the names.
One thought is that Windows Search might find these folders. If that does not work, then that just confirms my view that you need to take drastic action and to rename the folders.
Looking at Outlook's own search, I see that it has an option to search "In Folder". I don't have folders with that character in them. (I renamed my own folders with wonky characters because I found that they broke stuff.) But you could try that as a way of dining the folders. If Outlook is prepared to break the rules of Windows in naming files, maybe it will also break the rules when you want to find them.
